1. Field of the Invention
The present invention relates to dihydropyridine (DHP) calcium antagonist compounds, and more particularly to DHP calcium antagonist compounds, preparation methods, and medical applications for the treatment of cardiovascular diseases.
2. Description of the Related Art
Calcium antagonist, also known as calcium channel blocker, can be used for suppressing calcium influx across membranes and calcium release in cells, reducing the calcium ion concentration in the cells and the utility rate of calcium ions, suppressing the activity of adenosine triphosphatase (ATPase) activity, reducing cardiomuscular contraction force, relaxing smooth muscle cells dilating blood vessels, and lowering the resistance of peripheral blood vessels. Clinically, calcium antagonist is mainly used for the treatment of hypertension, angina, arrhythmia, dilated cardiomyopathy and ischemic heart disease, etc., and extensively used as a cardiovascular medicine. As increasingly more new medicines are introduced to the market, the DHP particularly catches our attention, since the DHP not only provides an excellent medical effect for lowering blood pressures, but also has little side effects, and a low price. The DHP has become a first-tier clinical medicine.
As the first DHP calcium antagonist nifedipine (1) launched to the market, its side-chain ester structure is electrically neutral, and thus having poor water solubility and absorption; and an amino side chain with a good water solubility is introduced to the nicardipine (2) ester group to give a better absorption effect, but it does not provide a long-lasting calcium antagonistic effect due to the first pass effect of the liver or the quick metabolism of the body. When we are looking for a new DHP medicine, a piperazine group using an aromatic branched chain is provided to substitute an amino structure of a side chain of an ester group in the structure of a substituted nicardipine medicine. With the fat solubility of the aromatic branched chain and the space hindrance of large substituent groups, the combination of medicines and receptors is affected to change the chemical properties of medicines and delay metabolism. According to this hypothesis, a series of DHP compounds with piperazine esters are synthesized.
